Methods for inhibiting the production of loose formation materials

ABSTRACT

As a representative embodiment of the methods of the invention disclosed herein, a through-tubing bridge plug having an expansible packing element and a tubular screen dependently coupled thereto is passed through a production string into a well bore therebelow and positioned adjacent to a perforated formation interval containing loose formation materials. The initial production of connate fluids from the well is controlled at a reduced rate for slowly drawing loose formation materials into the perforated well bore interval to at least substantially fill the annular space around the tubular screen with such formation materials. Then, once it is believed that the annular space around the tubular screen is filled with such loose formation materials, production of the well is commenced in the usual manner with the packed formation materials around the screen serving as a filter media to inhibit the entrance of further formation materials into the well bore.

United States Patent Urbanosky [4s] May 23, 1972 [72] Inventor: HaroldJ. Urbanoslty, Pearland, Tex.

[73] Assignee: Schlumberger Technology Corporation,

New York, N.\.

[22] Filed: Sept. 18, 1970 [21] Appl.No.: 73,277

[52] 11.5. C1. ..166/278, 166/285 [51] Int. Cl. ...,E21b 33/134, E21b43/04 [58] Field of Search ..166/278, 276, 51, 280, 285, 166/ 184, 187

[56] References Cited UNITED STATES PATENTS 2,725,107 11/1955 Abendrothet a1 166/51 2,745,496 5/1956 Blood et a1 166/1 87 X 2,775,303 12/1956Abendroth et al ..166/278 2,911,048 1 1/1959 Dublin et al. 166/290 X2,927,640 3/1960 Kenneday ..166/51 2,978,029 4/1961 OReilly et a1...166/187 X 3,130,787 4/ 1964 Mason ..166/184 X 3,460,618 8/1969 Blagg..166/ 184 3,559,736 2/1971 Bombardieri ..166/278 PrimaryExaminer-Stephen J. Novosad Anomey-Emest R. Archambeau, .lr., William J.Beard, Stewart F. Moore, David L. Moseley, Edward M. Roney and WilliamR. Sherman 57 ABSTRACT As a representative embodiment of the methods ofthe invention disclosed herein, a through-tubing bridge plug having anexpansible packing element and a tubular screen dependently .coupledthereto is passed through a production string into a well boretherebelow and positioned adjacent to a perforated formation intervalcontaining loose formation materials. The initial production of connatefluids from the well is controlled at a reduced rate for slowly drawingloose formation materials into the perforated well bore interval to atleast substantially fill the annular space around the tubular screenwith such formation materials. Then, once it is believed that theannular space around the tubular screen is filled with such looseformation materials, production of the well is commenced in the usualmanner with the packed formation materials around the screen serving asa filter media to inhibit the entrance of further formation materialsinto the well bore.

9 Claim, 4 Drawing Figures 1111;! i ililil-ilililililufiilip PATENTEDHM23 I972 FIG. 4

INVENTOR zm ATTORNEY Harold J. Urbanosky METHODS FOR INHIBITINGTHEPRODUCTION OF LOOSE FORMATION MATERIALS It is, of course, widelyrecognized that unconsolidated earth formations present serious problemsduring the usefulproduction life of many oil wells. For example, unlessappropriate preventative measures are taken, loose or unconsolidatedformation materials such as sand and the like will flow into the wellbore and eventually fill the well bore or else be carried to the surfaceby the produced fluids and damage production equipment. Thus, when awell of this nature is being completed, it is customary either to injectsuitable chemical consolidating agents into such loose formations orelse to place a screened liner in the well bore over the perforatedinterval. Once this is done, the production tubing and packer isinstalled and the well is placed on production.

Regardless of the particular completion technique initially employed, itis not at all uncommon for such wells to sooner or later begin producingsand and the like. When this happens, the usual practices employedheretofore require that the production string be pulled from the well topermit one or more of the typical recompletion procedures to beconducted for inhibiting further production of sand. It will beappreciated, therefore, that the removal of the production string andthe subsequent recompletion operations as well as the attendant loss ofproduction will represent a significant expense.

Accordingly, it is an object of the present invention to provide new andimproved methods for completing a well bore to preclude the entrance ofloose formation materials into the well bore as connate fluids are beingproduced.

This and other objects of the present invention are attained byarranging a tubular screen on the lower end of atubular body of athrough-tubing bridge plug having an expansible packing element. Thisassembly is lowered through a production string and into the well borebelow the lower end of the tubing string and production packer coupledthereto. The bridge plug is then set and the packing element expandednear the upper limit of a perforated unconsolidated formation intervalin the well bore so as to position the tubular screen within or adjacentto the unconsolidated interval. Production from the well is initiallycontrolled at a regulated retarded rate for slowly drawingunconsolidated formation materials into the well bore below the expandedpacking element. Once it is believed that at least a substantial portionof the annular space around the tubular screen and below the packingelement has been filled with such unconsolidated formation materials,production is then commenced in the usual manner. As a result, theunconsolidated formation materials which are initially admitted into thewell bore will thereafter serve as a permeable barrier for preventingthe subsequent entrance of additional loose formation materials into thewell bore as the well is being produced.

The novel features of the present invention are set forth withparticularity in the appended claims.

The invention, together with further objects and advantages thereof, maybe best understood by way of the following.

description of exemplary methods employing the principles of theinvention as illustrated in the accompanying drawings, in which:

FIGS. 1-4 successively illustrate a preferred manner of practicing thepresent invention.

Turning now to FIG. 1, a typical cased well bore is illustrated aspenetrating a producible unconsolidated earth formation 11. To gainaccess to the formation 11, one or more perforations, as at 12, havebeen previously produced with a typical perforating gun (not shown) forproviding fluid communication between the earth formation 1 1 and thecased well bore 10. As is customary, a production string including astring of small-diameter production tubing 13 is suspended in the wellbore 10 and its lower end extended through a typical production packer14 which is set therein above the perforations 12 for isolating theformation 11 from the well bore above the packer.

If, perchance, the well bore 10 extends a significant distance below theformation 11, in the practice of the present invention, a so-calledthrough-tubing bridge plug as at 15 (such asone-of those shown in eithera copending application Ser. No. 875,681 filed Nov. 12, 1969, or US.Pat. No. 3,460,6l8, U.S. Pat. No. 3,460,624, or US. Pat. No..3,460,625)is first set a short distance below the lower limits of the earthformation. Setting of the plug 15 will, of course, be accomplished asdescribed in those patents or in the application. Thus, after the plug15 has been-set, a supply-of cement, as at 16, is dumped into the wellbore 10 forcovering the uppennost portion of the plug to further assurethat there is no fluid communication between the perforated intervalofthe well bore and other earth formations therebelow. Inasmuch as thedetails of construction of theplug 15 as well as. its operation arefully explained in the aforementioned patents and application, it isbelieved unnecessary to describe these matters further.

It will, of course, be recognized that if either the bottom (not shown)of the well bore 10 is only a short distance below the lower limits ofthe formation 11 or a typical bridge plug has previously been set in thewell'bore below the formation, the through-tubing bridge plug 15 willnot be necessary. However, when it is necessary to block the well bore10 below the lower limits of the earth formation 11, in practicing thepresent invention it is preferred to employ one of those through-tubingbridge plugs as described in the aforementioned copending applicationand patents.

Turning now to FIG. 2, the lower portion of a second through-tubingbridge plug 17 is illustrated as it is being lowered through the welltubing 13 into the perforated interval of the well bore 10. In thepreferred manner of practicing the present invention, the through-tubingbridge plug 17 is similar to that shown in the aforementioned copendingapplication except that the lower portion of its body (as illustrated at98 in the application) has been replaced with an elongated tubularscreen 18 having a plurality of restricted openings such as small holesor narrow slots 19 formed therein to prevent the entrance of evenfinely-divided formation materials into the axial bore of the tubularbody. The bottom of the tubular body 18 is capped, as at 20, to blockits lower end.

In short, the slots 19 in the tubular screen 18 are cooperativelyarranged for straining fluids entering its axial bore so as to permitthe passage of only relatively sand-free fluids on through the centralmandrel 21 of the through-tubing bridge plug 17. In the preferred mannerof accomplishing this, the closed housing shown generally at 98 in thecopending application is replaced by the tubular screen 18. The timingmechanism 96 as Well as the valve 87", the spring 91 and the ports 86"shown in the aforementioned application are, of course, eliminated oromitted. Otherwise, the throughtubing bridge plug 17 is identical tothat shown and fully described in the copending application.

Accordingly, as illustrated in FIG. 3, the through-tubing bridge plug 17is lowered into the well bore 10 below the packer l4 and positioned sothat the tubular screen 18 will be disposed in the perforated intervalwith the uppermost end of the screen extending upwardly at least a shortdistance above the uppermost perforation 12. Once the bridge plug 17 ispositioned, it is operated as fully described in the aforementionedcopending application to expand the bag 22. As explained in thatapplication, the bag 22 is expanded by discharging a quantity of ahardenable fluent substance such as cement or the like into the interiorspace within the bag. Then, once the bag 22 is expanded into anchoringengagement within the well bore 10, the spring 23 will be effective formoving the opposite ends of the bag inwardly toward one another so as toform the expanded bag into a generally-toroidal configuration. In thismanner, the bridge plug 17 will be securely anchored in position topermit an additional quantity of cement, as at 24, to be deposited ontop of the bag 22. Thus, once the cement within the bag 22 as well asthat deposited on top of the bag, as at 24, has hardened, the mandrel 21will serve as a convenient fluid conduit between the tubing string 13thereabove and the interior bore of the tubular screen 18.

It will, of course, be recognized that once the bridge plugs 15 and 17are set at the lower and upper limits of the formation 11, sand andother loose formation materials can still readily enter the well bore byway of the perforations 12 even though the tubular screen 18 and themandrel 21 represent the sole communication passage between theperforated interval and the tubing string 13 thereabove. Accordingly, topractice the present invention, once the bridge plugs 15 and 17 are inposition, production of connate fluids from the formation 11 iscommenced at a slow, regulated rate which is calculated to be sufficientto only slowly draw sand and other unconsolidated formation materialsinto the perforated interval of the well bore 10 without risking damageto the tubular screen 18. Thus, by careful regulation of the initialrate of production from the well, a quantity of sand and the like, as at25, will be deliberately admitted into the perforated interval of thewell bore 10 so as to fill the annular space surrounding the tubularscreen 18 as schematically illustrated in FIG. 4. Then, once it isbelieved that the annular space around the tubular screen 18 has been atleast partially if not substantially filled with the sand 25, productionof the well may be commenced in the usual manner with the assurance thatno further quantity of sand will be produced since the sand that hasbeen packed into the annular space around the tubular screen 18 willserve as a porous filter media.

Accordingly, it will be appreciated that the present invention hasprovided new and improved methods for preventing the entrance ofunwanted loose formation materials into a well bore penetrating anunconsolidated formation. By arranging a tubular screen on the lower endof a typical through-tubing bridge plug, the entrance of loose formationmaterials into the Well bore is precluded without having to remove theproduction string to perform routine workover operations or withoutunduly hampering the production of connate fluids from the well.

While a particular mode of practicing the present invention has beenshown and described, it is apparent that changes and modifications maybe made without departing from this inven tion in its broader aspects;and, therefore, the aim in the appended claims is to cover all suchchanges and modifications as fall within the true spirit and scope ofthis invention.

What is claimed is:

l. A method for inhibiting the production of loose formation materialsfrom a well bore having a production string disposed therein andterminating above a perforated interval of the well bore traversing anearth formation containing such loose formation materials and comprisingthe steps of: lowering a tubular screen having its lower end covered anda flow passage in its upper end through said production string and intosaid perforated interval for positioning said tubular screen thereinwith its said flow passage below said production string and above theupper limit of said perforated interval; sealingoff the annular space insaid well bore around the upper end of said tubular screen for isolatingsaid perforated interval and leaving said flow passage as the sole fluidcommunication path between said production string and said perforatedinterval; producing an initial quantity of connate fluids from saidearth fonnation at a selectively-reduced flow rate for slowly drawingloose formation materials into said perforated interval until saidtubular screen is believed to be covered with said loose materials toprovide a filtering media of said loose materials around said tubularscreen; and, thereafter, producing additional connate fluids from saidearth formation through said filtering media and into said tubularscreen for straining subsequently-entering loose formation materialsfrom said additional connate fluids.

2. The method of claim 1 further including the initial step of:sealing-off said well bore below the lower limit of said perforatedinterval for isolating said perforated interval from the remainder ofsaid well bore therebelow before said tubular screen is lowered intosaid well bore.

3. The method of claim 2 wherein said initial step is performed bylowering a through-tubing plug through said production string and beyondsaid perforated interval for positioning said plug therebelow; settingsaid plug in position for isolating said perforated interval from saidremainder of said well bore; and discharging cement on top of said plugfor retaining said plug in its said position within said well bore.

4. A method for inhibiting the production of loose formation materialsfrom a well bore having a production string disposed therein andterminating above a perforated interval of the well bore traversing anearth formation containing such loose formation materials and comprisingthe steps of: lowering a through-tubing plug including a tubular bodywith a blocked lower end below a plurality of restricted openingstherein and having an expansible sealing member arranged around saidbody above said openings through said production string and into saidperforated interval for positioning said sealing member below saidproduction string and adjacent to the upper limit of said perforatedinterval; expanding said sealing member for isolating said perforatedinterval from said production string and arranging said tubular body asthe sole fluid conduit between said perforated interval and saidproduction string; initially producing connate fluids from said earthformation at a selectively-reduced flow rate for slowly depositing looseformation materials in said perforated interval around said tubular bodyto cover said restricted openings with a filtering media; and,thereafter, producing connate fluids from said earth formation throughsaid filtering media and into said tubular body for straining looseformation materials from connate fluids subsequently entering saidperforated interval.

5. The method of claim 4 further including the step of: depositing aquantity of cement around said tubular body above said sealing memberfor retaining said plug in position within said well bore.

6. A method for inhibiting the production of loose formation materialsfrom a well bore having a production string disposed therein andterminating above a perforated interval of the well bore traversing anearth formation containing such loose formation materials and comprisingthe steps of: lower ing a through-tubing plug including a tubular bodywith a blocked lower end below a plurality of restricted openingstherein and having an expansible sealing member arranged around saidbody above said openings through said production string and into saidperforated interval for positioning said sealing member below saidproduction string and adjacent to the upper limit of said perforatedinterval; discharging cement into said sealing member for expanding saidsealing member in said well bore around said tubular body to pack-offsaid perforated interval from said production string and leave saidtubular body as the sole fluid conduit between said perforated intervaland said production string; initially producing connate fluids from saidearth formation at a selectively-reduced flow rate for slowly depositingloose formation materials in said perforated interval around saidtubular body to cover said restricted openings with a filtering media;and, thereafter, producing additional connate fluids from said earthformation through said filtering media and into said tubular screen forstraining subsequently-entering loose formation materials from saidadditional connate fluids.

7. The method of claim 6 further including the intermediate step of:discharging an additional quantity of cement around said tubular bodyabove said sealing member once it is expanded for retaining said plug inposition within said well bore.

8. The method of claim 6 further including the initial step of:sealingoff said well bore below the lower limit of said perforatedinterval for isolating said perforated interval from the remainder ofsaid well bore therebelow before said throughtubing plug is lowered intosaid production string.

9. The method of claim 8 wherein said initial step is performed bylowering a first through-tubing plug through said production string andbeyond said perforated interval for positioning said first plugtherebelow; setting said first plug in position for isolating saidperforated interval from said remainder of said well bore; anddischarging cement on top of said first plug for retaining said firstplug in its said position within said well bore. 5

l l l

1. A method for inhibiting the production of loose formation materialsfrom a well bore having a production string disposed therein andterminating above a perforated interval of the well bore traversing anearth formation containing such loose formation materials and comprisingthe steps of: lowering a tubular screen having its lower end covered anda flow passage in its upper end through said production string and intosaid perforated interval for positioning said tubular screen thereinwith its said flow passage below said production string and above theupper limit of said perforated interval; sealing-off the annular spacein said well bore around the upper end of said tubular screen forisolating said perforated interval and leaving said flow passage as thesole fluid communication path between said production string and saidperforated interval; producing an initial quantity of connate fluidsfrom said earth formation at a selectively-reduced flow rate for slowlydrawing loose formation materials into said perforated interval untilsaid tubular screen is believed to be covered with said loose materialsto provide a filtering media of said loose materials around said tubularscreen; and, thereafter, producing additional connate fluids from saidearth formation through said filtering media and into said tubularscreen for straining subsequently-entering loose formation materialsfrom said additional connate fluids.
 2. The method of claim 1 furtherincluding the initial step of: sealing-off said well bore below thelower limit of said perforated interval for isolating said perforatedinterval from the remainder of said well bore therebelow before saidtubular screen is lowered into said well bore.
 3. The method of claim 2wherein said initial step is performed by lowering a through-tubing plugthrough said production string and beyond said perforated interval forpositioning said plug therebelow; setting said plug in position forisolating said perforated interval from said remainder of said wellbore; and discharging cement on top of said plug for retaining said plugin its said position within said well bore.
 4. A method for inhibitingthe production of loose formation materials from a well bore having aproduction string disposed therein and terminating above a perforatedinterval of the well bore traversing an earth formation containing suchloose formation materials and comprising the steps of: lowering athrough-tubing plug including a tubular body with a blocked lower endbelow a plurality of restricted openings therein and having anexpansible sealing member arranged around said body above said openingsthrough said production string and into said perforated interval forpositioning said sealing member below said production string andadjacent to the upper limit of said perforated interval; expanding saidsealing member for isolating said perforated interval from saidproduction string and arranging said tubular body as the sole fluidconduit between said perforated interval and said production string;initially produciNg connate fluids from said earth formation at aselectively-reduced flow rate for slowly depositing loose formationmaterials in said perforated interval around said tubular body to coversaid restricted openings with a filtering media; and, thereafter,producing connate fluids from said earth formation through saidfiltering media and into said tubular body for straining loose formationmaterials from connate fluids subsequently entering said perforatedinterval.
 5. The method of claim 4 further including the step of:depositing a quantity of cement around said tubular body above saidsealing member for retaining said plug in position within said wellbore.
 6. A method for inhibiting the production of loose formationmaterials from a well bore having a production string disposed thereinand terminating above a perforated interval of the well bore traversingan earth formation containing such loose formation materials andcomprising the steps of: lowering a through-tubing plug including atubular body with a blocked lower end below a plurality of restrictedopenings therein and having an expansible sealing member arranged aroundsaid body above said openings through said production string and intosaid perforated interval for positioning said sealing member below saidproduction string and adjacent to the upper limit of said perforatedinterval; discharging cement into said sealing member for expanding saidsealing member in said well bore around said tubular body to pack-offsaid perforated interval from said production string and leave saidtubular body as the sole fluid conduit between said perforated intervaland said production string; initially producing connate fluids from saidearth formation at a selectively-reduced flow rate for slowly depositingloose formation materials in said perforated interval around saidtubular body to cover said restricted openings with a filtering media;and, thereafter, producing additional connate fluids from said earthformation through said filtering media and into said tubular screen forstraining subsequently-entering loose formation materials from saidadditional connate fluids.
 7. The method of claim 6 further includingthe intermediate step of: discharging an additional quantity of cementaround said tubular body above said sealing member once it is expandedfor retaining said plug in position within said well bore.
 8. The methodof claim 6 further including the initial step of: sealing-off said wellbore below the lower limit of said perforated interval for isolatingsaid perforated interval from the remainder of said well bore therebelowbefore said through-tubing plug is lowered into said production string.9. The method of claim 8 wherein said initial step is performed bylowering a first through-tubing plug through said production string andbeyond said perforated interval for positioning said first plugtherebelow; setting said first plug in position for isolating saidperforated interval from said remainder of said well bore; anddischarging cement on top of said first plug for retaining said firstplug in its said position within said well bore.